ruby-on-rails – Rails：如何以百分比打印小数？

number_to_percentage(100)                                        # => 100.000%
number_to_percentage("98")                                       # => 98.000%
number_to_percentage(100,precision: 0)                          # => 100%
number_to_percentage(1000,delimiter: '.',separator: ',')       # => 1.000,000%
number_to_percentage(302.24398923423,precision: 5)              # => 302.24399%
number_to_percentage(1000,locale: :fr)                          # => 1 000,000%
number_to_percentage("98a")                                      # => 98a%
number_to_percentage(100,format: "%n  %")                       # => 100  %

选项：

:locale - Sets the locale to be used for formatting (defaults to current locale).

:precision - Sets the precision of the number (defaults to 3).

:significant - If true,precision will be the # of significant_digits. If false,the # of fractional digits (defaults to false).

:separator - Sets the separator between the fractional and integer digits (defaults to “.”).

:delimiter - Sets the thousands delimiter (defaults to “”).

:strip_insignificant_zeros - If true removes insignificant zeros after the decimal separator (defaults to false).

:format - Specifies the format of the percentage string The number field is %n (defaults to “%n%”).

或者你可以写一些如下的ruby：

class Numeric
   def percent_of(n)
    self.to_f / n.to_f * 100.0
   end
 end

p (1).percent_of(10)    # => 10.0  (%)
p (200).percent_of(100) # => 200.0 (%)
p (0.5).percent_of(20)  # => 2.5   (%)